After owning our C5 for almost 9 yrs, I got that message for the first time last week. I did some digging on the forums and found that Appliance PArts had a product that seemed to work, so I ordered it.
I've done about 20 mods to the car over the years. Some big, Most were small but wiring on these cars always get me a little nervous. the kit arrives and I get right to it.. the instructions are well laid out, ( you can tell whoever wrote them has gone through the process many times and have rewritten these instructions many times because the were spot on and even contained warnings on what mistakes to avoid.).
Not to make this thread longer than it needs to be but our problem included the column lock problem which required me to contact Tech Support and it was the smartest thing I did.. Because I got to talk to Richard... Not only has he mastered the process but he has excellent people skills. He walked me throuigh the 2 problems I had and because I didn't want to make a silly mistake... I'd call 3 or 4 times and he'd talk me through each step..
Long story longer than it needed to be but we're back on the road and Thanks to Richard and Compliance Parts

 

The LMC5 is a great product and solves the pull key, and service column problems by duplicating the physical process of how the hardware works.